Dextromethorphan Versus Placebo for Neuropathic Pain

Herpes Zoster Clinical Trial

Official title:

Dextromethorphan Versus Placebo for Neuropathic Pain

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00001344
• Other study ID #: 930114
• Secondary ID: 93-D-0114
• Status: Completed
• Phase: Phase 2
• First received: November 3, 1999
• Last updated: March 3, 2008
• Start date: March 1993
• Est. completion date: February 2001

Study information

• Verified date: March 2000
• Source: National Institutes of Health Clinical Center (CC)
• Contact: n/a
• Is FDA regulated: No
• Health authority: United States: Federal Government
• Study type: Interventional

Clinical Trial Summary

In our current clinical trial, we are comparing the effects of two NMDA receptor antagonists to placebo in patients with painful distal symmetrical diabetic neuropathy or post-herpetic neuralgia. The treatments in this three-period crossover study are dextromethorphan, up to 920 mg/day (about 8 times the antitussive dose), memantine, 30-50 mg/day, and placebo. Memantine is an NMDA antagonist used in Europe to treat Parkinson's disease and Alzheimer's disease. The underlying hypothesis, based on studies of painful neuropathies in animal models, is that neuropathic pain is caused largely by sensitization of central nervous system neurons caused by excitatory amino acid neurotransmitters, acting largely through NMDA receptors. A previous small trial of dextromethorphan suggested efficacy in diabetic neuropathy pain. The study requires one visit to the NIH outpatient Pain Research Clinic, and consists of three 9-week treatment periods. Patients who respond to one of the medications will be invited to participate in further controlled studies of the medication followed by up to several years of open-label treatment under continued observation.

Description:

In our current clinical trial, we are comparing the effects of two NMDA receptor antagonists to placebo in patients with painful distal symmetrical diabetic neuropathy or post-herpetic neuralgia. The treatments in this three-period crossover study are dextromethorphan, up to 920 mg/day (about 8 times the antitussive dose), memantine, 30-50 mg/day, and placebo. Memantine is an NMDA antagonist used in Europe to treat Parkinson's disease and Alzheimer's disease. The underlying hypothesis, based on studies of painful neuropathies in animal models, is that neuropathic pain is caused largely by sensitization of central nervous system neurons caused by excitatory amino acid neurotransmitters, acting largely through NMDA receptors. A previous small trial of dextromethorphan suggested efficacy in diabetic neuropathy pain. The study requires one visit to the NIH outpatient Pain Research Clinic, and consists of three 9-week treatment periods. Patients who respond to one of the medications will be invited to participate in further controlled studies of the medication followed by up to several years of open-label treatment under continued observation.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 129
• Est. completion date: February 2001
• Accepts healthy volunteers: No
• Gender: Both
• Age group: N/A and older

Eligibility

Patients must be over 18 years of age.

Patients must have a definite diagnosis of diabetic neuropathy or post herpetic neuralgia or a diagnosis of neuropathic pain of various etiologies other than diabetic neuropathy or post herpetic neuralgia.

Duration of symptoms must be at least 3 months.

Severity of pain must be at least mild, if constant; or at least moderate, if intermittent and at least 2 hours duration a day.

Patients using tricyclics, narcotics, or antiseizure medications, must keep the drug dosages constant throughout the study.

No patients with unstable disease process; i.e., angina pectoris, accelerated hypertension, recent stroke or transient cerebral ischemia, uncontrolled seizures.

No pregnant or lactating women. Women of child bearing potential must use birth control pills, intrauterine device, or barrier contraceptive devices.

No history of significant drug abuse or PCP use. No history of IV drug abuse, prescription drug abuse, or alcoholism.

No significant liver or kidney disease.

No MAO inhibitors.

No cognitive impairment or language difficulty as judged by difficulty completing pain diary, medical history, or telephone conversation.

Patients must not have any other chronic pain condition that gives them pain greater than the neuropathy pain.

Study Design

Endpoint Classification: Safety/Efficacy Study, Primary Purpose: Treatment

Related Conditions & MeSH terms

• Diabetic Neuropathies
• Herpes Zoster
• Neuralgia

Intervention

Drug:
• dextromethorphan

Locations

Country	Name	City	State
United States	National Institute of Dental And Craniofacial Research (NIDCR)	Bethesda	Maryland

Sponsors (1)

Lead Sponsor	Collaborator
National Institute of Dental and Craniofacial Research (NIDCR)

Country where clinical trial is conducted

United States, 

References & Publications (3)

Albers GW, Sáenz RE, Moses JA Jr, Choi DW. Safety and tolerance of oral dextromethorphan in patients at risk for brain ischemia. Stroke. 1991 Aug;22(8):1075-7. — View Citation

Bakshi R, Faden AI. Competitive and non-competitive NMDA antagonists limit dynorphin A-induced rat hindlimb paralysis. Brain Res. 1990 Jan 15;507(1):1-5. — View Citation

Choi DW. Dextrorphan and dextromethorphan attenuate glutamate neurotoxicity. Brain Res. 1987 Feb 17;403(2):333-6. — View Citation